best way to add anchor link to top of page on very long page

Hello - I need to create a “up to top” anchor link for this page ( htttp://clais.macmillan.yale.edu/links ) . This is a very long page - is there a way to have a “floating anchor link to the top” on this page? What is the best way to do this?

And, is it better to break this page apart and have each category on it’s own page? Does that help SEO?

TIA - Lisa.